Content data, such as video data representing a video feature such as a television show or programme, film, movie or the like, may be supplied to a media centre of an end user or viewer as a free-to-air broadcast or as encrypted broadcast to be decrypted by a set top box or the like of the end user. Such content data may also be delivered to an end user on a recording medium such as a DVD or may be streamed to or downloaded by the end user via the Internet or other network (for example a telecommunications network) via TCP/IP, UDP or other appropriate network protocols.
There are several business models by which content data may be delivered, including purchase, rental, periodic, e.g. monthly, subscription and advertisement-supported. Advertisement-supported content data delivery where the content is free at the point of delivery, but the end user or viewer is subjected to periodic advertisements, is similar to traditional broadcast commercial television in which a video feature is periodically interrupted by advertisements. Moreover, advertisement-supported content data delivery does not require personal detail gathering or any credit card transactions to enable the service. For these reasons, advertisement-supported content data delivery may be more immediately acceptable to the end user or consumer.
One problem with advertisement-supported content data delivery is that it may be difficult to ensure that the end user actually experiences the advertisement because they may simply the skip over the advertisements by ‘jumping’ in non-linear time using a personal video recorder (PVR) or media centre computer software or cut out the advertisements from previously downloaded content data. For example, many hard disk based television receivers have a recording buffer to permit the user to pause live television and, provided there is sufficient data in this buffer, it is possible to ‘skip’ any advertisements which are presented during the programme. The possibility that the end user may be able to avoid experiencing the advertisements will of course reduce the value to the advertiser and thus the revenue that the content data deliverer can derive from the advertiser.